See the USAtoa Forum pages for
Don's original descriptions and methods.

Everything needs a name
so I named this with Don's initials since he came up with it!

This describes a duplication
based on Don's original design and his findings on the prototype.

The history of this antenna
relates to the scarce 2000 Mu ferrite cores needed for this type antenna to work
well. By gluing 5 smaller rods in series, Don made it possible to
create a core that works just as well as if it was made to that length.
That is the tricky part of this whole project. This is the only part you
have to take great care with during construction. It's easy if you know
what to do!

1. The rods need to be obtained
from the link on the forum pages. Make sure you get the right ones!
5 rods are needed for each antenna. The surplus dealer is A1 to do
business with!

2. Construct your assembly jig.
A 90 degree V will hold the rods while you glue them together. Put
wax paper on that with a good corner in the paper to prevent sticking to the
jig.

3. Here you have two choices.
Both have been made to work. You can use crazy glue or Epoxy. Don
had bad luck with the crazy glue and went to Epoxy. After discussing the
reason for the crazy glue having problems, shrink was put on first to
support the rods before winding. With the crazy glue you can't
bend the antenna with any force at all or it will break. You could do a
chin up on it if you pull straight down! It has almost no shear strength
is the reason why. Carefully place the glued stick into the smallest
shrink tubing you can fit over it. Then carefully heat each end first, so
that it encloses the ends of the rod. That allows the shrink to pull the
rod toward the middle as the rest is heated to shrink it. Be very careful
not to heat beyond the point that it shrinks to size, preventing damage to
the glue. Epoxy is some bit stronger in this respect but makes a thicker
wall between rods, but either will do. You will need different sizes of
shrink tubing for different layers.

4. Once the shrink is in place
use 23-28 AWG enamel wire to wrap the antenna the full length except for 1/4
inch or so on the ends. The exact number of loops is not critical!
Just try to make it even with side by side windings. I just happened to
have 23 AWG wire and that has been proven to work well.

5. Once you have the windings in
place you can put a shield over them. Double some aluminum foil the length
of the windings. Make a piece that will go the length and wrap around the
core leaving 1/8th inch gap the full length. Prepare a bare wire the
length of the antenna plus lead length. That becomes the shield's
connecting wire. Place a new length of shrink over the winding layer and shrink
in place. Careful of the heat! Now place the foil shield into place
down the length of the antenna making sure it does not short across the
gap anywhere. Put the bare wire down the length of the foil on the non gap
side of the foil. Now we will put a shrink tubing cover over that
and shrink into place. If necessary you can use some electrical tape to keep the
shield in place while you do this.

6. The finished antenna should
look like this. The silver ring on the end is the shield.

BE VERY CAREFUL NOT TO PUT
SIDEWAYS PRESSURE ON THIS ANTENNA UNTIL YOU GET IT IN A SUPPORTING TUBE.
But with the layers of shrink and the windings it is actually not too tender
anymore and will still work even if a rod should come unglued but not damaged
any other way.

Ready for shrink/shield/ and
shrink again

Note:
Use electrical tape to hold the wires

until you get shrink tubing
on it.

Results after construction

DF-1 single layer Ferrite DIY Antenna specifications.

Tested at 1,10,100 kHz

1 kHz

L=6.773 mH

C=3.740 uf.

R=3.183 Ohms

Z=42.65 Ohms

Q=13.3

10kHz

L=6.124 mH

C= 41.44 NF

R=18.81 Ohms

Z=383.6 Ohms

Q=20.1

100 kHz

L=6.124 mH

C= 417.8 PF

R=180.0 Ohms

Z=3.52 K Ohms

Q=20.6

When connected to a Red
TOA system this antenna had very good performance. Compared to the Flat
Panel V.2 the gain is lower but performed very well with higher amp. gain.

If space and location are
driving needs, this antenna should serve you well on the TOA net.

A double layer version of this
antenna has been constructed for testing but has not yet been fully tested.
From what I see, it won't be necessary.

Note:
The key to this project is finding 2000 mu or more ferrite core material.
It's rare and expensive in long lengths! These rods are government surplus that
may not last long! Other ferrite materials should be highly suspect as to
their performance for our use on TOA. Here is all that is known about this
source taken from the recommended supplier.